Why Are Tomato Seedlings Not Growing?

All gardeners can and will experience successes and failures as well. It Is very disappointing that you sow the tomato seeds and nurture the seedling and these are not growing how you would expect.

tomato seedlings not growing

So, why are tomato seedlings not growing? This article will help you to find out the reasons why your seedlings can stop growing and what to do when this happens.

Sometimes there is no problem at all, it is just the variety. Some varieties grow faster than others.

In some cases, there are factors that you cannot control like a cat is digging up your seedlings, but there are things that you can control and can mean a lot for your seedlings if done properly.

Now, let’s see what are the reasons why the tomato seedlings can stop growing.


Improper watering such as under watering or overwatering can cause the tomato seedling growth stunt.

Tomato seedlings will stop growing if they are under-watered. Tomato plants love to have moisturized soil. These plants are heavy feeders; therefore, their root system grows deep in the soil.

To ensure that all the roots get enough water, you should soak the soil way down into the ground. If the roots are not getting enough moisture, they are unable to absorb the nutrients from the soil.

The early signs of under watering your seedlings, before they stop growing, are wilting leaves (which is the earliest sign), yellow leaves and dry soil.

Overwatering your seedlings is not a good idea either. This can also cause stunted growth because if there is too much water in the soil, the roots cannot breathe.

If the roots are unable to breathe, these will rot and die, so, your seedlings will not grow properly or even die as well. When the root system is affected, the plant will not get enough nutrients; therefore’ your seedlings will stop growing.

If you tend to underwater or over water the tomato seedlings then you should fix this problem. Checking the soil regularly can help you decide whether to water or not.

Stick your finger into the soil a few inches so you can feel if it is wet or not. When the soil is dry, then you should water the seedlings, but if the soil is still wet, that means it doesn’t need watering, so check it the next day again.

It is a good idea to use containers with proper draining holes for your seedling. This helps the excess water to drain and the roots are protected from rotting.


Temperature is another very important factor for the tomato seedlings and if this is too hot or too cold then your seedlings will be affected and will stop growing.

Usually, cold temperatures are more likely to affect your tomato seedlings than hot temperatures. Most of the people are growing seedlings at the end of the winter, beginning of spring.

In this period, you will not face hot temperatures unless you are growing your seedlings indoors.

So, if you grow the seedling indoors, then you should not place them next to the radiator or fireplace, as these can get too much heat. When it is too hot, the soil dries out way too quickly and will result in underwatered seedlings.

If you think that the hot temperature is the problem, you should change your seedlings’ place, or water more frequently to ensure proper hydration.

Too cold temperatures are affecting tomato seedlings’ growth as well. No one likes to get cold, right? Tomato plants are not doing well if the temperatures are below 10°C/ 50°F. These will stop growing because they cannot provide enough energy for growth.

If you are growing your seedling indoors, then it is easy, because you can control the room temperature easily. However, when the seedlings are growing outside, in the ground, then it is more complicated.

You can’t control the weather and the outside temperatures, but you can protect the seedlings from the low temperatures.

When the seedlings are small, you can just cut the bottom of a clear plastic bottle and place it over the seedling. This way you create a greenhouse and your seedling will be protected. Or if the seedlings are larger, you can use a row cover to protect them from the cold.

Poor Soil Conditions

When you sow your tomato seeds, you should use special soil for this. However, not all soils are of good quality, even if the seller says so.

Soil pH

A soil that has an improper pH, lacking nutrients or has too many nutrients and minerals, can all affect your seedlings in their growth.

When the soil has a high or low pH, this will affect the roots and the plant will not get enough nutrients. It is best to have a pH range for tomato seedlings’ soil of 6.0 to 6.8 (slightly acidic).

But how do you know these measures? The only way to find out is to do a soil test. You can send some of your soil to a local agricultural extension or you test it yourself with a pH test kit.

If the soil pH is too low (acidic), then you can amend it by adding some calcium carbonate to it. But if the soil pH is too high (alkaline), you can lower it if you add sulphur to the soil.


Excessive or not enough nutrients can cause a growth stunt in your seedlings. If one of these two problems arise, your tomato plants’ leaves will turn yellow as well.

If the soil is lacking nutrients, the seedling will not have the energy to grow and become strong; therefore, if you think this is the problem, you can add fertilizer to the soil.

However, too much fertilizing can affect seedlings in a bad way.

Wrap Up

When you see your tomato seedlings are not growing, you should check for the above. Maybe they feel too hot or too cold and they don’t have enough energy to grow.

Or if there is too much water in the soil, that can be the issue, so you can just stop watering for a while and leave the soil to dry out.

However, before starting to find out what is the problem, you should first think about what type of tomato seedling you have. Whether is a fast-growing variety or a slower one.

If you know that your seedling should grow faster, then you should research the problem. But, maybe the variety of your seedling is a slow-grower tomato, then you are just impatient and you should give the plant some time to mature.



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